Upgrading Router to Support APRX 2.00

After a few emails from APRSIS Server administrators complaining that my iGate was over logging on telemetry. I decided it was time to either take my igate down, or upgrade it. For some reason, at random intervals, it would belch out a blank telemetry burst every second. The only fix was a reboot, which I automated, but it happened every few days, grumble grumble grumble.  

I attempted to download an APRX 2.00 package and install it with little success. Then after I researched a bit more, I found that the newest release candidates of OpenWRT supported APRX 2.00 in its available packages. I figured, I could just update to the latest, and run the easy package install from the web interface. I also remembered how I would have to re-install X-WRT web interface to make it all easy, but getting there would be tricky. I dug around a bit more and found images of the newer OpenWRT with X-WRT integrated. That version didn't have the version of APRX I wanted in the available packages, but I still decided this would be worth a try.

	First I downloaded the image with X-WRT integrated, and went through the firmware upgrade path. This maintains the main settings of the router. It was a bit frustrating, because it doesn't reboot itself, or tell you to reboot it, so I waited at least 20 minutes, and powered it off and back on. The new version was online, with my network settings intact.
Next, I dug through the newest version of the packages from the openwrt.org site, and fed the URL into the web interface. The package installed successfully, and I was able to start rebuilding the config file.
	Excerpts of my config file: mycall  KI6PSP-10 # APRS-IS server name and portnumber. server    socal.aprs2.net    14580 server    southwest.aprs2.net    14580 server    aprsca.net    14580 #filter "possibly multiple filter specs in quotes" filter "m/1"    serial-device /dev/tts/1  9600 8n1    KISS    callsign     $mycall  # callsign defaults to $mycall    #tx-ok        false    # transmitter enable defaults to false    initstring "\xC0\xC0\xFF\xC0\r\nMO 0\rKISS $01\r" beaconmode aprsis beacon symbol "R&" lat "3536.84N" lon "11741.06W" \      comment "PHG0130/WRT54GL w/APRX 2.00-iGate Rx Only" beaconmode aprsis beacon raw ">TinyTrak4(KISSTNC)-WRT54GL iGate" beaconmode aprsis beacon raw ">SysOp:KI6PSP@GMAIL.COM" beaconmode aprsis beacon raw ">http://KI6PSP.BLOGSPOT.COM"

Now I have the capability to add a real radio to this setup, and either 2-way iGate, and/or Digipeat. Hopefully I wont have problems with the random telemetry belches again.

--
KI6PSP (Ed)

2-way APRS Communications Vs. Rx Only iGates

I operate a iGate at my house, and a Digi/iGate on the local mountain top. I reciently got a TinyTrak4 with a display unit, and was attempting to send an email via APRS, and I wanted to share what I learned, what I did, and the eventual results.

2 Rx Only iGates in town, and a Wide1-1 Digi on the hill that also gates. I found several options for sending an email, but I wanted to make sure that 2 way communication via this method was possible. If I am out camping in one of my favorite areas, there is no repeaters to get into, but I might be able to get my Digi. The ability to communicate out of the area is important, as it is near Death Valley and no cell phone coverage.

Here are the instructions for sending email via APRS that I found, I used the 1st one because of the 2 way option, but the 2nd one is a little easier to remember how to use without a cheat sheet.

http://www.aprsca.net/email.html
http://www.aprs-is.net/Email.aspx

When sending messages, I noticed that I wouldn't always get the Acknowledge back. I checked my paths and the local iGates were gating my traffic to the APRS-IS, but because my iGate is a RX-Only, and the other one has the Transmitter disabled, I figured the return traffic was never being sent to RF.

I started researching filters used for iGates, and I found that my gate was not sending any filter commands to the servers it was connecting to, except range. So when the packet would return to my iGate, it would just be discarded. Even if it was handed to the TNC, I am using a scanner as a reciever, so there is no transmitter. I added in the following to the filter string, "t/p". The reason was positions usually only travel to the APRS-IS cloud. When you apply a filter, you are basically telling the APRS-IS server what you want from it or can handle. Now when I send a message, and my iGate picks me up, the Acknowledge is sent by the full iGate/Digi on the hill.

Ref: http://aprs-is.net/javAPRSFilter.aspx

So the big thing that I learned here, is RX-Only iGates must have the filters set properly as to not inhibit 2-way communication via APRS. Now if I can convince the owner of the other iGate in town to add that filter line to his login string....
Ed
KI6PSP

WRT54GL APRS RxOnly iGate w/OpenWRT & APRX

I wanted to build myself an iGate should the other one in town go offline. I began by purchasing a WRT54GL from Fry's and I re-flashed it with a Kamikaze version of OpenWRT. I bought a TinyTrak4 and flashed it with just the KISS TNC Firmware. The TinyTrak4 fit nicely into the case, with the small fan on the top, and the TTL Converter on the serial side of the TT4. The version I had was an older version, and I kept it in the case so it wouldn't get shorted out on the router board, it takes up more space, but I don't have to worry about it. I installed the small fan because I have discovered how much heat these can generate, especially if the modem is stacked with it. I couldn't do an easy plug on the top of the board to the header pins because of the TT4 case, so I had to solder to the bottom of the board to the contact points, that way I could enclose the whole setup inside the original case. Once I planed and installed the cables the way I wanted, I was able to get the whole package closed, and still be able to see the TT4 lights. I ran a small cable to the back of the case, so I could use a simple audio jumper into the cheapo scanner I was going to use as the receiver. I just used a Realistic Handheld scanner that only has 10 memories. It's perfect for APRS, because we only need max 2 channels. 144.390 MHz and the alternate 144.990 MHz.

I installed OpenWRT and During my research, I discovered X-WRT. It is a replacement web interface that allows you do just about anything you need to via the web. SSH console no longer needed once X-WRT is installed. I wanted to use APRS4r, but when I attempted to get that installed, I quickly ran out of memory, because Ruby (a dependency) is rather large. I don't know how to build my own OpenWRT image, so I started digging around and found APRX, it was in the package listings for the OpenWRT. I really didn't have to learn that much linux, because X-WRT has a file editor that allowed me to modify the files I needed without using the command line. I did have to use the command line to install the X-WRT interface though.

The version of APRX on the packages for OpenWRT was version 0.99. I configured that up, and got it to connect to the APRSIS, and start gating traffic. I did later run into a problem because I didn't have a filter setup in the configs. When you attempt 2-way communication via APRS, you must have a filter on the RX-Only iGates or the APRSIS will think it can send traffic back through your iGate, using the reverse path. APRS-IS filters are a way of telling the server you are connecting to, what you want from it. If you tell it you only want position packets, then the 2-way message traffic will find another way back to that originating station, even though you gated it.

APRS-IS Filters:

http://aprs-is.net/javAPRSFilter.aspx

The following are examples of the filters. The aprx.conf file shows the filter command like this:

aprsis-filter "m/100 t/p"

However, I noticed that it always ignored it, until I added a few spaces into the line like this:
aprsis-filter            "m/100 t/p"

Verify that the server accepted your filter by connecting to it via http://server:14501 and look for your iGate callsign, the filter will be on the "SA Setting" column.

***Replace "server" with the name of the server you are connecting to. IE: socal.aprs2.net
***If you use the default "rotate.aprs.net", you will have to look up which server you are connected to. It may require a Google search, as some servers are named differently. Use http://aprs.fi to find out which server you are talking to (IE: APRS via TCPIP*,qAC,T2SOCAL), then google it. IE: T2SOCAL is actually socal.aprs2.net, so you would use http://socal.aprs2.net:14501/

APRX 0.99 version configs:
aprsis-server    socal.aprs2.net    14580
aprsis-server    southwest.aprs2.net    14580
aprsis-server    aprsca.net    14580
aprsis-filter            "m/100 t/p"
radio serial   /dev/tts/1  9600 8n1    KISS  callsign KI6PSP-10
netbeacon for KI6PSP-10 symbol "R&" lat "3536.84N" lon "11741.06W"
comment "PHG0130/WRT54GL w/APRX-iGate Rx Only"
netbeacon ">TinyTrak4(KISSTNC)-WRT54GL iGate"
netbeacon ">SysOp:KI6PSP@GMAIL.COM"

Example Configs that I changed from default on APRX 2.00 and above:
mycall KI6PSP-10
server    socal.aprs2.net    14580
server    southwest.aprs2.net    14580
server    aprsca.net    14580
filter "m/1" #Had problems with it not accepting multiple filters, Gate all RX, reject APRSIS to RF beyond 1km of location.
serial-device /dev/tts/1 9600 8n1 KISS
callsign $mycall # callsign defaults to $mycall
#tx-ok false # transmitter enable defaults to false
initstring "\xC0\xC0\xFF\xC0\r\nMO 0\rKISS $01\r"
beaconmode aprsis
beacon symbol "R&" lat "3536.84N" lon "11741.06W" \
comment "PHG0130/WRT54GL w/APRX 2.00-iGate Rx Only"
beaconmode aprsis
beacon raw ">TinyTrak4-WRT54GL iGate"
beaconmode aprsis
beacon raw ">SysOp:KI6PSP@GMAIL.COM"
beaconmode aprsis
beacon raw ">http://KI6PSP.BLOGSPOT.COM"

TinyTrak4 Website:
http://www.byonics.com/tinytrak4/

Serial to 3.3v TTL converter:
http://www.compsys1.com/workbench/On_top_of_the_Bench/Max233_Adapter/max233_adapter.html

WRT54 Setup Ref:
http://www.dimebank.com/cak/k6dbg/k6dbg_igate.html
http://jdc.parodius.com/wrt54g/serial.html

APRX Ref:
http://ham.zmailer.org/oh2mqk/aprx/

X-WRT Install Info:
http://wiki.x-wrt.org/index.php/Kamikaze_Installation